Urea amidolyase is an ATP dependent HCO minus 3 requiring, biotin containing urea cleaving enzyme complex found in certain fungi and algae. The proposed research would be represented by the following points: 1. Purification of the enzyme complex to homogeneity or near homogeneity. 2. Dissociation of the enzyme complex into active components catalyzing particular reactions of the urea cleavage process. 3. Characterization of these active components as to molecular weight, subunit makeup, as well as enzymatic properties of the separated enzyme components. 4. Characterization of carboxyl transfer process of the urea carboxylase component of the enzyme complex (Enzyme-biotin-CO2, carboxylation of urea).